Ground-based Exoplanet Detection

ground-based exoplanet detection

Artists rendition of 55 Cancri e

Astronomers have for the first time done a ground-based exoplanet detection observing the transit of a planet in front of its host star.

Exoplanets, planets orbiting a distant star have become a common day-to-day occurrence these days. As of today more than 1773 exoplanets have been discovered in 1160 planetary systems. The most common way to detect these orbiting exoplanets is by measuring the dimming of a host star when a planet passes in front of it, called transit photometry. The dimming is extremely minute and requires very sensitive instruments to measure, that’s why it’s usually done from space to avoid interference from our atmosphere. Now astronomers at Harvard-Smithsonian Center for Astrophysics have detected an exoplanet using a ground-based telescope .

Ground-based Exoplanet Detection

This is the First time detection of an exoplanet using transit photometry with a ground-based telescope. The exoplanet 55 Cancri e was detected by astronomers using a 2.5 m Nordic optical telescope on the island of La Palma. A feat that usually requires a space telescope.

The host star called 55 Cancri is 40 light-years from earth, visible to the naked eye. The planet was previously detected using radial velocity measurements. This time the planet was detected on its transit in front of the star, dimming it an extremely slight 0.05% for almost two hours. Astronomers estimate the size of the planet to about twice that of earth, 16,000 miles in diameter.

The planet 55 Cancri e is about eight times as massive as earth and revolves with a period of 18 hours. It’s the innermost of five planets in the Cancri solar system. Unfortunately there’s no hope for life on the planet since dayside temperatures reach over 1700 degrees Celsius.

This method of ground-based exoplanet detection raises the prospect of being able to use ground-based telescopes to find and characterize large extrasolar planets in the future despite the difficulties presented by earths atmosphere. This fills a need since space telescopes wont be able to keep track of the growing number of detected exoplanets orbiting distant stars in the near future.

Image credit: NASA/JPL